1. Field of the Invention
The present invention relates generally to a bone grinding apparatus adapted to automatically cut bone into bone tissue powder for application in medical procedures.
2. Description of the Prior Art
Numerous medical procedures require the donation of human organs and tissues. Bone is one of the required human tissues needed for many of these medical procedures. Among other uses, donated bone samples are used as adhesives and grafting material in bone grafting operations, as protective layers in prosthetic implants, and as bone tissue composites in the creation of screws, disks, plates, pins, and joint sockets used in corrective surgeries. Regardless of the ultimate form in which donated bone is used, donated bone samples must first be processed by a grinding apparatus into bone tissue powder. The bone tissue powder is then demineralized and used in the previously mentioned capacities to facilitate the medical operation.
Several attempts have been made to create devices that correctly mill the bone samples into a useable powder form. Numerous issues have arisen that have complicated this process. First of all, conventional bone grinding systems require a two stage milling operation using separate pieces of equipment. These prior art devices lack the ability to transform the donated sample directly into bone tissue powder. This requires the bone to be ground first into intermediary pieces within one grinding apparatus, and then the pieces must be physically transferred to a second apparatus that then converts the pieces into the bone tissue powder form required in medical procedures. Since these prior art devices require multiple pieces of equipment, which necessitates a transfer of the bone specimen between the pieces of equipment, these prior art devices fail to adequately and efficiently transform the precious gift of human bone into the needed bone tissue powder.
A second drawback of conventional bone grinding systems is the likelihood of contamination of the bone sample during the grinding process. Throughout the grinding process, the bone sample must remain in a sterile environment. Conventional bone grinding devices fail to adequately protect that sterile environment due to the drive portion of these devices being physically located in the same area as the dispensing portion. For example, Grooms U.S. Pat. No. 5,918,821 has the motor portion of the grinding apparatus in close proximity to the dispensing portion. Thus, numerous samples of bone tissue run a high risk of contamination during the operation of the Grooms"" apparatus. Also, any maintenance or repair work on any portion of the Grooms"" grinding apparatus requires the entire apparatus be removed from the surgical environment in order to maintain a sterile medical facility. Therefore, the Groom""s patent fails to adequately prevent the contamination of bone tissue, which is detrimental to the sterility requirement of bone tissue powder in medical applications.
Attempts to alleviate this contamination issue have been unsuccessful in the past. For example, Dowd U.S. Pat. No. 5,607,269 discloses a bone grinding apparatus that has its drive system enclosed in a box. This box initially separates the drive portion of the grinding apparatus from the location where the bone is processed. However, once the bone has been processed, the Dowd invention still requires the bone to be brought through the same environment that contains the drive mechanism before the ground bone is used for its medical purpose. Therefore, the Dowd patent fails to address the contamination issues associated with the processed bone and the drive mechanism for the grinding apparatus sharing the same surgical environment.
Another problem associated with grinding bone into usable bone tissue powder is the breakdown of morphogenetic proteins, which leads to a reduction in osteoinductivity. Osteoinductivity is a characteristic of bone tissue powder necessary to make the bone tissue powder useful within the human body. Morphogenetic proteins are the main element within the bone that maintains osteoinductivity. The major enemy to the morphogenetic proteins is the heat produced during the grinding process. The heat produced in most grinding devices is unchecked due to the lack of a controlled automated process that regulates the speed of the cutting elements and the pressure and rate at which the bone sample is fed to the cutting elements.
For example, the Grooms patent requires a human user to manually press on a plunger in order to supply the bone to its grinding elements. This manual process fails to maintain a consistent pressure or speed with which the bone sample is supplied to these grinding elements.
The Dowd apparatus also fails to maintain a consistent pressure or speed of the bone sample during the grinding process. The Dowd patent uses a holding vice to support the bone sample as a drill bit shaves off bone particles. The processing portion of the Dowd apparatus is not pressurized and lacks the controlled environment necessary in creating a consistent pressure and speed of the bone sample supplied to the grinding element. Thus, the Dowd device also fails to efficiently maintain the Osteoinductive characteristic of the bone sample used in the grinding process.
Thus, there is a need for an automated bone grinding apparatus adapted to sterilely process bone into bone tissue powder for use in medical procedures.
The present invention provides a bone grinding apparatus, which comprises a grinding chamber, primary and secondary cutting elements positioned within the grinding chamber to sequentially perform primary and secondary cutting operations on the bone, and a drive mechanism operatively engaging the primary and secondary cutting elements. The apparatus also includes a bone supplying cylinder engaging the grinding chamber and adapted to transport the bone to the cutting elements at a consistent pressure. A sealing component operatively engages the drive mechanism and separates the drive mechanism from the cutting elements.
A method for grinding bone is also disclosed. This method includes the steps of providing a sequentially arranged plurality of cutting tools and rotating a first cutting tool and a second cutting tool in the same direction, thereby creating a shearing action between the first cutting tool and the second cutting tool. The method also teaches supplying a bone sample to the cutting tools and dispensing that sample in bone tissue powder form.
A main purpose of this bone grinding apparatus is to efficiently and effectively convert human cortical bone into bone tissue powder for use in many medical procedures. In order to arrive at the bone tissue powder, an apparatus and method for efficiently and effectively cutting donated human cortical bone into the bone tissue powder is required. Key characteristics of any apparatus and method that would effectively and efficiently process human cortical bone into bone tissue powder would include automation, sterilization, and retention of the osteoinductivity of the bone during the conversion process. Also, it is extremely important not to waste any of the donated human cortical bone during the cutting process, due to the limited supplies of suitable bone available for conversion into bone tissue powder.
It is therefore a general objective of the present invention to provide a bone grinding apparatus designed to convert bone into bone tissue powder.
Another objective of the present invention is to provide a bone grinding apparatus that converts human cortical bone into bone powdered tissue and retains the osteoinductive characteristic of the bone.
Still another object of this invention is to automate the process of converting bone into bone tissue powder.
Still yet another object of the present invention is the efficient collection and dispersion of bone tissue powder once the bone sample has been processed into said powder.
Another object of the present invention is to environmentally separate the driving mechanism of a bone grinding apparatus from the other portions of the bone grinding apparatus that come in contact, or in close proximity, with the bone sample or bone tissue powder during the conversion process.
Still yet another object of the present invention is the combination into one grinding apparatus all required steps to reduce human cortical bone into bone tissue powder.